  // 竖向轮播图
  var swiper = new Swiper('.swiper3', {
    spaceBetween: 30,
    centeredSlides: true,
    direction: 'vertical',
    autoplay: {
      delay: 2500,
      disableOnInteraction: false,
    }
  });

  // 导航的吸顶
  var tit = document.getElementById("nava");
  var tittop = tit.offsetTop;
  window.addEventListener("scroll",function () {
    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
    //console.log(scrollTop);
    if (scrollTop > tittop) {
      tit.style.position = "fixed";
      tit.style.top = "0px";
      // 这是一个累加
      tit.style.cssText += "z-index:999";
     
    } else {
      tit.style.position = "static";
    }
  });
   
  // 侧边栏当前元素
  var bodyHeight = document.documentElement.clientHeight;
  var box = document.getElementById("box");
  window.onscroll = function () {
    var scrollTop = document.documentElement.scrollTop || document.body.scrollTop;
    if (scrollTop > bodyHeight) {
      box.style.display = "block";
    } else {
      box.style.display = "none";
    }
    
    // 回到顶部
    
    $(".box_b").click("click",function(){
      $('body,html').stop().animate({scrollTop:0},500);
      return false;
    })
  }